let's try not to clog up this thread, guys, there's plenty of good talk about "ki" here...

Ki is energy: energy is work: work is the rate of change of power: power is directly related to force.

therefore, in my opinion, Ki indirectly comes from a force. this means that without some sort of force, Ki will not exist. this is from a scientific standpoint.

from a spiritual standpoint, you have to look at Ki differently. if someone attacks you, you have to stop seeing an opponent, and start seeing energy flowing towards you. merge with it, control it to your heart's desire, then set it free. this is how I would definte "manipulating Ki," and it's how i understand Aikido